I. Technical Field of the Invention
The present invention relates to the field of corn breeding. In particular, the invention relates to inbred corn seed and plants designated GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B and FBMU, and derivatives and tissue cultures of such inbred plants.
II. Description of the Background Art
The goal of field crop breeding is to combine various desirable traits in a single variety/hybrid. Such desirable traits include greater yield, better stalks, better roots, resistance to insecticides, pests, and disease, tolerance to heat and drought, reduced time to crop maturity, better agronomic quality, and uniformity in germination times, stand establishment, growth rate, maturity, and fruit size.
Breeding techniques take advantage of a plant""s method of pollination. There are two general methods of pollination: a plant self-pollinates if pollen from one flower is transferred to the same or another flower of the same plant. A plant cross-pollinates if pollen comes to it from a flower on a different plant.
Corn plants (Zea mays L.) can be bred by both self-pollination and cross-pollination. Both types of pollination involve the corn plant""s flowers. Corn has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in corn when wind blows pollen from the tassels to the silks that protrude from the tops of the ears.
Plants that have been self-pollinated and selected for type over many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny, a homozygous plant. A cross between two such homozygous plants produce a uniform population of hybrid plants that are heterozygous for many gene loci. Conversely, a cross of two plants each heterozygous at a number of gene loci produces a population of hybrid plants that differ genetically and are not uniform. The resulting non-uniformity make performance unpredictable.
The development of uniform corn plant hybrids requires the development of homozygous inbred plants, the crossing of these inbred plants, and the evaluation of the crosses. Pedigree breeding and recurrent selection breeding methods are used to develop inbred plants from breeding populations. Those breeding methods combine the genetic backgrounds from two or more inbred plants or various other broad-based sources into breeding pools from which new inbred plants are developed by selfing and selection of desired phenotypes. The new inbreds are crossed with other inbred plants and the hybrids from these crosses are evaluated to determine which of those have commercial potential.
The pedigree breeding method for single-gene traits involves crossing two genotypes. Each genotype can have one or more desirable characteristics lacking in the other; or, each genotype can complement the other. If the two original parental genotypes do not provide all of the desired characteristics, other genotypes can be included in the breeding population. Superior plants that are the products of these crosses are selfed and selected in successive generations. Each succeeding generation becomes more homogeneous as a result of self-pollination and selection. Typically, this method of breeding involves five or more generations of selfing and selection: S1xe2x86x92S2; S2xe2x86x92S3; S3xe2x86x92S4; S4xe2x86x92S5, etc. After at least five generations, the inbred plant is considered genetically pure.
Backcrossing can also be used to improve an inbred plant. Backcrossing transfers a specific desirable trait from one inbred or source to an inbred that lacks that trait. This can be accomplished for example by first crossing a superior inbred (A) (recurrent parent) to a donor inbred (non-recurrent parent), which carries the appropriate gene(s) for the trait in question. The progeny of this cross are then mated back to the superior recurrent parent (A) followed by selection in the resultant progeny for the desired trait to be transferred from the non-recurrent parent. After five or more backcross generations with selection for the desired trait, the progeny are heterozygous for loci controlling the characteristic being transferred, but are like the superior parent for most or almost all other genes. The last backcross generation would be selfed to give pure breeding progeny for the gene(s) being transferred.
A single cross hybrid corn variety is the cross of two inbred plants, each of which has a genotype which complements the genotype of the other. The hybrid progeny of the first generation is designated F1. Preferred F1 hybrids are more vigorous than their inbred parents. This hybrid vigor, or heterosis, is manifested in many polygenic traits, including markedly improved higher yields, better stalks, better roots, better uniformity and better insect and disease resistance. In the development of hybrids only the F1 hybrid plants are sought. An F1 single cross hybrid is produced when two inbred plants are crossed. A double cross hybrid is produced from four inbred plants crossed in pairs (Axc3x97B and Cxc3x97D) and then the two F1 hybrids are crossed again (Axc3x97B)xc3x97(Cxc3x97D).
The development of a hybrid corn variety involves three steps: (1) the selection of plants from various germplasm pools; (2) the selfing of the selected plants for several generations to produce a series of inbred plants, which, although different from each other, each breed true and are highly uniform; and (3) crossing the selected inbred plants with unrelated inbred plants to produce the hybrid progeny (F1). During the inbreeding process in corn, the vigor of the plants decreases. Vigor is restored when two unrelated inbred plants are crossed to produce the hybrid progeny (F1). An important consequence of the homozygosity and homogeneity of the inbred plants is that the hybrid between any two inbreds is always the same. Once the inbreds that give a superior hybrid have been identified, hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parents is maintained. Conversely, much of the hybrid vigor exhibited by F1 hybrids is lost in the next generation (F2). Consequently, seed from hybrid varieties is not used for planting stock. It is not generally beneficial for farmers to save seed of F1 hybrids. Rather, farmers purchase F1 hybrid seed for planting every year.
North American farmers plant over 70 million acres of corn at the present time and there are extensive national and international commercial corn breeding programs. A continuing goal of these corn breeding programs is to develop high-yielding corn hybrids that are based on stable inbred plants that maximize the amount of grain produced and minimize susceptibility to environmental stresses. To accomplish this goal, the corn breeder must select and develop superior inbred parental plants for producing hybrids.
In one aspect, the present invention provides corn plants designated, separately, GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B and FBMU. Also provided are corn plants having the functional and morphological characteristics of corn plants GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU, as exemplified by corn plants having all the physiological and morphological characteristics of corn plants GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU.
The inbred corn plants of the invention may further comprise, or have, a cytoplasmic factor that is capable of conferring male sterility. Parts of the corn plants of the present invention are also provided, such as, e.g., pollen obtained from an inbred plant and an ovule of the inbred plant.
The invention also concerns seed of the corn plant NL054B; which have been deposited with the ATCC. The invention thus provides inbred
corn seed designated NL054B and having ATCC Accession No. PTA-3679.
The inbred corn seed of the invention may be provided as essentially homogeneous populations of inbred corn seed designated GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU. Essentially homogeneous populations of inbred seed are those that consist essentially of the particular inbred seed and are generally purified free from substantial numbers of other seed, so that the inbred seed forms between about 90% and about 100% of the total seed, and preferably, between about 95% and about 100% of the total seed. Most preferably, an essentially homogeneous population of inbred corn seed will contain between about 98.5%, 99%, 99.5% and about 100% of inbred seed, as measured by seed grow outs.
In any event, even if a population of inbred corn seed was found, for some reason, to contain about 50%, or even about 20% or 15% of inbred seed, this would still be distinguished from the small fraction of inbred seed that may be found within a population of hybrid seed, e.g., within a bag of hybrid seed. In such a bag of hybrid seed offered for sale, the Governmental regulations require that the hybrid seed be at least about 95% of the total seed. In the practice of the present inventors, the hybrid seed generally forms at least about 97% of the total seed. In the most preferred practice of the inventors, the female inbred seed that may be found within a bag of hybrid seed will be about 1% of the total seed, or less, and the male inbred seed that may be found within a bag of hybrid seed will be negligible, i.e., will be on the order of about a maximum of 1 per 100,000, and usually less than this value.
The populations of inbred corn seed of the invention are further particularly defined as being essentially free from hybrid seed. The inbred seed populations may be separately grown to provide essentially homogeneous populations of inbred corn plants designated GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU.
In another aspect, the present invention provides a tissue culture of regenerable cells of inbred corn plant GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU. The tissue culture will preferably be capable of regenerating plants having the physiological and morphological characteristics of one of the foregoing inbred corn plants, and of regenerating plants having substantially the same genotype as one of the foregoing inbred corn plants. Preferably, the regenerable cells in such tissue cultures will be embryos, protoplasts, meristematic cells, pollen, leaves, anthers, roots, root tips, silk, flowers, kernels, ears, cobs, husks or stalks. Still further, the present invention provides corn plants regenerated from one of the tissue cultures of the invention.
In another aspect, the present invention provides for single gene converted plants of GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU. The single transferred gene may preferably be a dominant or recessive allele. Preferably, the single transferred gene will confer such traits as male sterility, herbicide resistance, insect resistance, resistance for bacterial, fungal, or viral disease, male fertility, enhanced nutritional quality, and industrial usage.
In yet another aspect, the present invention provides processes for preparing corn seed or plants, which processes generally comprise crossing a first parent corn plant with a second parent corn plant, wherein at least one of the first or second parent corn plants is the inbred corn plant designated GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU. These processes may be further exemplified as processes for preparing hybrid corn seed or plants, wherein a first inbred corn plant is crossed with a second, distinct inbred corn plant to provide a hybrid that has, as one of its parents, the inbred corn plant GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU.
In a preferred embodiment, crossing comprises planting, in pollinating proximity, seeds of the first and second parent corn plant, and preferably, seeds of a first inbred corn plant and a second, distinct inbred corn plant; cultivating or growing the seeds of said first and second parent corn plants into plants that bear flowers; emasculating the male flowers of the first or second parent corn plant, i.e., treating the flowers so as to prevent pollen production, in order to produce an emasculated parent corn plant; allowing natural cross-pollination to occur between the first and second parent corn plants; and harvesting the seeds from the emasculated parent corn plant. Where desired, the harvested seed is grown to produce a corn plant or hybrid corn plant.
The present invention also provides corn seed and plants produced by a process that comprises crossing a first parent corn plant with a second parent corn plant, wherein at least one of the first or second parent corn plants is the inbred corn plant designated GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B or FBMU. In one embodiment, corn plants produced by the process are first generation (F1) hybrid corn plants produced by crossing an inbred in accordance with the invention with another, distinct inbred. The present invention further contemplates seed of an F1 hybrid corn plant.
In certain exemplary embodiments, the invention provides the following F1 hybrid corn plants and seed thereof:
hybrid corn plant designated DK706, having GMLEA and 6F905, both inbreds of the invention, as parents;
hybrid corn plant designated DK446, having 91CSV-1 and 01ASB1, both inbreds of the invention, as parents;
hybrid corn plant designated DK604, having WDAQ2 and 01IBH2, both inbreds of the invention, as parents;
hybrid corn plant designated DK527, having 01IBH2 and FBMU, both inbreds of the invention, as parents;
hybrid corn plant designated DK474, having 91DFA-5 as one inbred parent;
hybrid corn plant designated DK642, having WDDQ1 as one inbred parent;
hybrid corn plant designated DK560, having 85DGD1 as one inbred parent;
hybrid corn plant designated DK566, having PHEI4 as one inbred parent;
hybrid corn plant designated DK442, also having 01IBH2 as one inbred parent; and
hybrid corn plant designated DK626, having NL054B as one inbred parent.
It should be noted here that although the present invention provides 12 inbreds, the details concerning only 10 exemplary hybrids are set forth herein. This results from the crossing of certain of the claimed inbreds with other inbreds of this invention. Four hybrids are disclosed herein that have both parents from the presently claimed inbreds, namely DK706, DK446, DK604, and DK527. Also, the inbred 01IBH2 is employed to generate three different, particularly successful hybrids. Accounting for these various combinations results in the ten hybrids disclosed herein that have commercially advantageous features. Table 30 is provided herein for instant cross-reference of the disclosed inbreds and exemplary hybrids.
In yet a further aspect, the invention provides inbred genetic complements of corn plants designated, separately, GMLEA, 6F905, 91CSV-1, 91DFA-5, WDAQ2, WDDQ1, 85DGD1, PHEI4, 01ASB1, 01IBH2, NL054B and FBMU. The phrase xe2x80x9cgenetic complementxe2x80x9d is used to refer to the aggregate of nucleotide sequences, the expression of which sequences defines the phenotype of, in the present case, a corn plant, or a cell or tissue of that plant. An inbred genetic complement thus represents the genetic make up of an inbred cell, tissue or plant, and a hybrid genetic complement represents the genetic make up of a hybrid cell, tissue or plant. The invention thus provides corn plant cells that have a genetic complement in accordance with the inbred corn plant cells disclosed herein, and plants, seeds and diploid plants containing such cells.
Plant genetic complements may be assessed by genetic marker profiles, and by the expression of phenotypic traits that are characteristic of the expression of the genetic complement, e.g., isozyme typing profiles. Thus such corn plant cells may be defined as having an RFLP genetic marker profile in accordance with the profile shown in Table 52, Table 53, Table 54, Table 55, Table 56, Table 57, Table 58, Table 59, Table 60, Table 61, Table 62 or Table 63; or a genetic isozyme typing profile in accordance with the profile shown in Table 64, Table 65, Table 66, Table 67, Table 68, Table 69, Table 70, Table 71, Table 72, Table 73, Table 74 or Table 75; or having both an RFLP genetic marker profile and a genetic isozyme typing profile in accordance with the profiles shown in Tables 52 and 64; Tables 53 and 65; Tables 54 and 66; Tables 55 and 67; Tables 56 and 68; Tables 57 and 69; Tables 58 and 70 ; Tables 59 and 71; Tables 60 and 72; Tables 61 and 73; Tables 62 and 74; or as shown in both Tables 63 and 75.
In another aspect, the present invention provides hybrid genetic complements, as represented by corn plant cells, tissues, plants and seeds, formed by the combination of a haploid genetic complement of an inbred corn plant of the invention with a haploid genetic complement of a second corn plant, preferably, another, distinct inbred corn plant. In another aspect, the present invention provides a corn plant regenerated from a tissue culture that comprises a hybrid genetic complement of this invention.